1. Field of the Invention
The present invention relates to a toner image printing apparatus comprising a combination of a first case and a second case, the first case being provided with a printing mechanism for forming a toner image on a sheet-type recording medium, while the second case is adapted to receive on its top surface the first case and has a recording medium supply mechanism capable of supplying sheets of the recording medium to the printing mechanism in the first case.
In recent years, a remarkable progress has been achieved in the field of information processing systems represented by computers, and compact systems with high operation speeds have become available. Image reproducing apparatus, typically printers, connected to such systems also have been developed and, nowadays, electrophotographic apparatus such as laser beam printers are used widely.
In general, this type of image reproducing apparatus employs a primary recording medium on the surface of which an electrostatic latent image corresponding to the information to be printed is formed. The electrostatic latent image is then developed by a toner to form a toner image which is then transferred to a secondary recording medium. Usually, cut sheets are used as the secondary recording medium. The cut sheets are stored in a sheet cassette and extracted therefrom one by one so as to be fed to the printing apparatus. The sheet cassette is demountable from the apparatus in order to allow supply of cut sheets to the cassette. In order to minimize the size of the apparatus, in a common design of the apparatus, the sheet cassette is mounted on the apparatus in such a manner that the rear end portion of the sheet cassette projects outwardly from the body of the apparatus.
The cut sheets to which the toner image has been transferred and fixed are ejected from the apparatus body one after another, usually through an ejection opening formed in one side of the body of the apparatus, and are stacked on a tray provided adjacent to the ejecting opening. In some known apparatus, the cut sheets ejected through the ejection opening are conveyed to the upper side of the apparatus body so as to be stacked in a tray provided on the top of the apparatus body in a face-down state. i.e.. in such a manner that the printed image faces downward
In the image reproducing apparatus of the kind described, as well as in ordinary toner image printing apparatus such as copying machines, the quantity of the information to be printed varies according to the conditions of use. Namely, it is necessary that a large quantity of sheets are supplied as required in order to cope with occasional demands for printing a great deal of information. To comply with such a requirement, a toner image printing apparatus has been proposed which has a combination of a first case provided with a printing mechanism for forming a toner image on a sheet and a second case adapted to receive on its top the first case and having a sheet supplying mechanism for supplying the printing mechanism with the sheets. This type of toner image printing apparatus has been disclosed, for example, in Japanese Patent Unexamined Publication Nos. 63-70269 and 60-122645.
The toner image printing apparatus of this type may be designed such that the opening for mounting a sheet cassette on the second case and the sheet ejection opening in the first case are provided on the same side of the apparatus. With such a design, it is difficult to find any space for mounting a sorter adjacent to the sheet ejection opening, because the rear portion of the sheet cassette projects from the apparatus under of the ejection opening. On the other hand, when the design is such that the sheets are ejected and stacked in face-down state on the top of the apparatus, an inconvenience is caused that the sheet cassette is accessible for demounting only in the direction which is opposite to the direction in which printed sheets are accessed.